Green tea extract

Does it work?

• -A little, and mostly from the caffeine that rides along with it. Pooled trials show green tea extract nudges body weight down by roughly 1 kg over 12+ weeks — but meta-analysis found that effect only when caffeine was present; catechins (EGCG) stripped of caffeine moved nothing. It's a mild thermogenic helper, not a fat-loss tool. Diet and a real calorie deficit do the work.

How much · when

• -If you want to try it: ~300-500 mg EGCG per day, paired with caffeine (the combo is what trials actually measured).
• -Effects only show up over 12 weeks or more, and they're small — treat it as a marginal add-on, not a strategy.
• -Plain caffeine alone gets you most of the same thermogenic bump for far less money. Coffee or a green tea habit covers it.

The catch

• -Decaffeinated catechins barely register. The 2010 AJCN meta-analysis found weight and waist benefits with caffeine present, and no anthropometric benefit at all when caffeine was removed.
• -The Cochrane review pooled ~1,945 people and called the weight loss statistically non-significant and 'not likely to be clinically important' — and useless for keeping weight off.
• -The ~1 kg signal is the kind of effect that disappears once you account for the caffeine and the calorie deficit doing the lifting.

Better option

• -Skip the extract — get the caffeine directly (coffee or plain caffeine) and put your money toward a protein target and a sustainable deficit, which is what actually drives fat loss.

Safety

• -High-dose green tea extract (especially fasted, concentrated EGCG pills) has been linked to rare but real liver injury — the supplement form, not brewed tea, is the concern. Take it with food and don't megadose.
• -It contains caffeine, so it stacks with coffee, pre-workout, and other stimulants — count it toward your daily total to avoid jitters and sleep problems.
• -Catechins can reduce iron absorption; if you're managing low iron, keep it away from iron-rich meals and supplements.

Key research

• Effect of green tea catechins with or without caffeine on anthropometric measures: a systematic review and meta-analysisAm J Clin Nutr · 2010 · Meta-analysis
• Green tea for weight loss and weight maintenance in overweight or obese adultsCochrane Database Syst Rev · 2012 · Systematic review
• The effects of green tea extract supplementation on body composition, obesity-related hormones and oxidative stress markers: a grade-assessed systematic review and dose-response meta-analysis of randomised controlled trialsBr J Nutr · 2024 · Meta-analysis
• Does green tea catechin enhance weight-loss effect of exercise training in overweight and obese individuals? A systematic review and meta-analysis of randomized trialsJ Int Soc Sports Nutr · 2024 · Meta-analysis
• The effect of green tea extract on fat oxidation at rest and during exercise: evidence of efficacy and proposed mechanismsAdv Nutr · 2013 · Review

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